This invention relates to a lubrication system for two-cycle internal combustion engines and more particularly to an improved and simplified lubricating system for such engines.
As is well known with two-cycle type engines, the fuel/air charge is introduced into the crankcase for compression and transfer to the cylinders. Frequently, lubricant is mixed with the fuel so that the components of the engine can be lubricated without the need for a separate lubricant pump and delivery system. Such an arrangement offers simplicity for the engine and cost reduction. However, there are some disadvantages in mixing lubricant with the fuel for lubricating the engine. First of all, the consumption of lubricant may be higher than with systems having separate lubricating arrangements. Also, under some running conditions, there is a danger of lack of sufficient lubrication for certain components of the engine. For example, under low speed running, there may be insufficient lubrication for the crankshaft journals and the connecting rod crankshaft journals. The lubrication problem is particularly prevelant when the engine is operated with fuels having low lubricity such as kerosene or the like. Although positive lubricating systems will overcome these difficulties, the use of a separate, positive lubricating system adds to the complexity and further requires the assurance that sufficient lubrication will be provided through all running conditions. This is normally accomplished by employing an expensive oil pump that has an output related to engine speed and load.
It is, therefore, a principal object of this invention to provide an improved lubricating system for two-cycle internal combustion engines.
It is a further object of the invention to provide a two-cycle lubricating system in which lubricant is mixed with the fuel and delivery to the critical components is insured under all running conditions.